1. Field of the Invention
The present invention relates to card fastening mechanisms and more particularly to an improved mechanism for releasably fastening a card in an expansion slot on the motherboard of a microcomputer.
2. Description of Related Art
A conventional AGP card fastening arrangement is shown in FIG. 10. As shown, an elongated expansion slot 90 comprises a lever 91 pivotably formed at one end and two lengthwise grooves 94. A card 92 comprises a recess 93 at one end of its connector side. To install the card 92, insert the connector of the card 92 into the grooves 94. Next, pivot the lever 91 to the end to clamp the card 92 in the recess 93.
However, the prior art suffered from several disadvantages. For example, a relatively large space is required to perform the lever pivoting. Also, such pivoting is somewhat difficult since little space is available after inserting the connector of the card 92 into the expansion slot 90. It is often that the fastening is not reliable. As such, the fastening may be compromised after a short time of use, particularly in a vibratory environment.
Taiwanese Patent Publication No. 453,461 discloses another AGP card fastening arrangement as detailed below. An AGP expansion slot 2 comprises a projected rail 21 at either side, the rail 21 having a length less than half of the total length of the expansion slot. A hole 211 is formed at an inner end of the rail 21. A U-shaped frame 22 comprises a groove 221 at an inner surface of either side arm, a tab 222 at an open end of the groove 221, and a raised cross member 223 interconnected both side arms. The frame 22 and the rails 21 form a slide with the grooves 221 being slidable along the rails 21. After inserting an AGP card 3 into the expansion slot 2, push the frame 22 toward the expansion slot 2 until the tabs 222 enter the holes 211 and the cross member 223 receives in a cavity 31 at one end of the connector side of the card 3 for fastening the card 3. It is understood that a reverse operation can detach the card 3 from the expansion slot 2.
However, the patent suffered from several disadvantages. For example, the coupling of the expansion slot 2 and the frame 22 depends on the slide. Unfortunately, due to limited space reason, both the grooves 221 and the rails 21 are much relatively small elements, resulting in a difficulty of precisely assembling them together. To the worse, a slight deflection of either arm of the frame 22 may compromise the desired mated engagement of the grooves 221 and the rails 21. As stated above, the card 3 is fastened after pushing the frame 22 toward the expansion slot 2 with the tabs 222 entered the holes 211 and the cross member 223 received in the cavity 31. However, such pushing may be difficult since the coupled grooves 221 and the rails 21 cannot provide a sufficient support force thereto. In an extreme condition, at least one of the grooves 221 and the arms of the frame 22 is deformed, dislodged, or even broken. It is also understood that the positioning of the frame 22 with respect to the expansion slot 2 depends on the engagement of the tabs 222 and the holes 211. However, such positioning is not reliable since contact areas of the tabs 222 and the holes 211 are much more relatively small. It is often that a slight vibration of the card 3 may dislodge the frame 22, resulting in failure of the positioning. In addition, a click indicating an exact engagement of the tabs 222 and the holes 211 is hardly heard during the pushing operation. It is more often that a user may push the frame 22 excessively to dislodge the tabs 222 from the holes 211 and the user is often not aware of it. Thus, the need for improvement still exists.